1. Field of the Invention
The present invention relates to a safety securing device to be used, when a driver leaves the seat of an industrial vehicle, such as a fork lift.
2. Description of Related Arts
An operator or driver of an industrial vehicle, such as a fork lift, is engaged in not only driving the vehicle but also loading. The driver therefore frequently leaves the seat of the vehicle, when the performance of other work makes it necessary. In this case, the key of the vehicle may be kept swiched on. When an industrial vehicle is equipped with a special attachment, for example, the driver must leave the driver's seat and manipulate a hydraulic lever for loading, while keeping the vehicle in a stopped position. In this case, it is very dangerous, if the driver does not revert the forward or reverse shift lever to a neutral position before leaving the driver's seat.
A safety device exists for use on an electric vehicle, that provides a seat switch for detecting the presence or absence of the driver on the seat, and a switch for de-energizing the power source of the main circuit, upon detection of the driver's absence with the seat switch. When this safety device is applied to a vehicle with an internal combustion engine, such as a gasoline engine or Diesel engine, the engine automatically stops upon the driver's leaving of a vehicle but must be restarted manually. This manual re-starting operation is as frequent as the driver's leaving the seat and is troublesome in the case of an internal combustion engine.
There is a proposed device that allows a vehicle to be kept in the stop position while the engine is operating. That is, the power source of the solenoid valve for switching the forward and reverse movement, is de-energized by means of a seat switch upon the driver's leaving the seat, and the shift lever is reverted to a neutral position by a spring. Upon implementing this proposed device, when a driver leaves the vehicle while the shift lever is in a forward or reverse position and then again takes a seat, the seat switch detects the presence of the driver and immediately energizes the power of the solenoid valve. In this case, however, the vehicle, which is idling, may run away due to a creep phenomenon of the torque-converter. The proposed device mentioned above therefore involves a danger.